Don Lapre -- the self-proclaimed "King of Infomercials" -- was found dead in his Arizona jail cell early Sunday morning of an apparent suicide ... just days before he was set to go on trial for allegedly selling millions of dollars of bogus vitamins.
Lapre, who has been a fixture on early AM TV hocking various products, was facing 41 counts of conspiracy, mail fraud, wire fraud and promotional money laundering for selling a product called, "The Greatest Vitamin in the World."
The FDA begged to differ, concluding that Lapre was making wild claims about the vitamin that were simply unsupported by the evidence.
It's unclear how Lapre killed himself, but a spokesman for the U.S. Marshals Service says officials are investigating the situation.
Lapre had been accused of screwing roughly 220,000 people out of nearly $52 million in a national vitamin scam.
The 47-year-old shot to stardom with a scheme involving classified ads in newspapers.